Flexible polyurethane material

ABSTRACT

The present invention provides a flexible two component polyurethane and method for producing the polyurethane. The cured polyurethane is flexible, durable and weather resistant. The polyurethane is suitable for use as a protective layer on various substrates. The flexible polyurethane is the reaction product of solvent-free reaction components. The first component includes one or more polyols, optionally, one or more diols, and a catalyst. The second component includes a primary aliphatic isocyante crosslinker.

This is a divisional of application Ser. No. 09/064,490, filed Apr. 22,1998 which is now U.S. Pat. No. 6,258,918.

FIELD OF THE INVENTION

This invention relates to a flexible, polyurethane material, moreparticularly, to a solvent free, two-component polyurethane and, evenmore particularly, to such a polyurethane which is transparent andexhibits improved flexibility, durability and weatheringcharacteristics. The present invention also includes an articleutilizing the polyurethane as a top coat, and a method of making such apolyurethane top coat.

BACKGROUND OF THE INVENTION

Decorative articles often utilize a polyurethane top coat to cover orprotect a base substrate and any indicia or decorative features locatedon the substrate. The articles may include various substrates upon whichprinting or profiled graphics have been applied. The polyurethanematerial is generally clear or optically transparent and functions as alens in order to display the substrate or any indicia applied thereon.The decorative articles have a wide variety of uses in both interior andexterior applications. For example, model names for automobiles areoften displayed in a decorative manner on an exterior surface of thevehicle. The polyurethane covers and protects the indicia displayed onthe model nameplate.

Polyurethanes are generally applied onto articles or substrates as asolution or flowable reaction mass which is then cured to form a lens.The flow characteristics of the uncured polyurethane are important indeveloping a polyurethane coating at a sufficient and desired thicknessupon curing.

Some polyurethanes, upon curing, are rigid, non-flexible polymers. Therigidity of the article is often due to the chemical structure of thecomponents used in the formulation of the polyurethane. Rigidpolyurethanes are susceptible to abrasion and scratching. Additionally,the materials do not demonstrate an appropriate level of self-healing.Self-healing describes the ability of the polyurethane to return to itsoriginal shape or appearance after being deformed, such as byscratching.

Polyurethanes are applied onto various types of substrates. However,some specific substrates are not suitable for use with conventionalpolyurethanes. Some substrates are susceptible to absorbing an amount ofmoisture which can react with the polyurethane to form bubbles in thecured polyurethane. The formation of bubbles in the polyurethane istermed outgassing. For polyurethanes containing an isocyanate,outgassing may also occur when certain porous substrates, for examplepolyvinyl chloride, are backed with adhesives containing carboxylgroups. The porous substrate permits the reaction of the isocyanate inthe polyurethane with carboxyl groups in the adhesive. This reactionresults in the release of carbon dioxide which generally becomes trappedin the polyurethane. The occurrence of outgassing in a curedpolyurethane is aesthetically undesirable.

Conventional two-component polyurethanes are typically either solventbased or utilize polyethers as the primary hydroxyl source. The solventbased polyurethanes are generally not viscous enough to provide adesired thickness to the polyurethane lens. Additionally, solvent basedpolyurethanes, when applied as top coats, do not permit the completeevaporation of the solvent from the polyurethane. The incompleteevaporation can produce striations, parting lines, or bubbles in thepolyurethane and therefore result in an aesthetically unacceptable topcoat. Polyether based polyurethane mixtures can provide suitableflexible properties. However, they tend to degrade and yellow whenexposed to sunlight. Thus, existing polythane compositions, and methodsfor producing them, often result in undesirable finished properties orare unsuitable for exterior applications.

There is a need to provide a polyurethane that is flexible, durable, andweather resistant. Additionally, such a polyurethane should beapplicable to various substrates without experiencing a substantialamount of outgassing. A polyurethane having the noted properties wouldbe suitable for use a protective coating on various substrates for bothinterior and/or exterior applications.

SUMMARY OF THE INVENTION

The present invention provides a two component polyurethane, an articleutilizing the polyurethane, and a method of making the polyurethane. Thecured polyurethane is flexible, durable and weather resistant. Theoptically transparent polyurethane is suitable for use as a protectivecoating on various substrates.

The polyurethane of the present invention has primary aliphaticisocyanate crosslinking. The polyurethane is the reaction product of tworeaction components. The first reaction component includes one or morepolyols. The polyol portion of the first component has an equivalentweight in the range from about 28 to about 3000. The first componentalso includes one or more diols having an equivalent weight in the rangefrom about 30 to about 4000. The desired diol is a combination of ashort chain diol, having an equivalent weight in the range from about 30to about 400, and a polymeric diol, having an equivalent weight in therange from about 400 to about 4000. Polyol and diol compounds suitablefor use in the first component may include polyesters, polycarbonates,polyacrylates, polyalkylenes, and polyethers, or combinations thereof.Additionally, a catalyst is included in the first component.

The second component includes a primary aliphatic polyisocyanatecrosslinker. The noted polyisocyanate preferably represents at leastabout 50 weight percent of the total isocyanate present in the secondcomponent. The first and second components are combined to form asolvent-free admixture which may then be applied onto a desiredsubstrate and cured. The viscosity of the admixture is generally in therange of about 400 cps to about 5000 cps at 25° C. The viscosity of thematerial enables the formation of a lens, or meniscus, over thesubstrate.

The cured, optically transparent polyurethane is flexible, durable andweather resistant. The flexibility of the polyurethane is demonstratedthrough the Shore A hardness test, the flexural modulus test, and thestorage modulus test. The polyurethane has a Shore hardness of less than94, a storage modulus of 1.0×10⁸ pascals or less, and a flexural modulusof 1.0×10⁸ pascals or less.

The durability and weather resistant properties of the present inventionare demonstrated through such tests as the Hoffman scratch resistancetest and the heat aging test. The polyurethane of the present inventionhas a surface with a Hoffmnan scratch-hardness test result of 2 or less.Additionally, the polyurethane exhibits a color shift value of 1 or lesswhen subjected to the heat aging test.

It would be an advantage to provide a polyurethane that is flexible,durable, and weather resistant. A polyurethane having the notedproperties would be suitable for use as a protective layer for bothinterior and exterior applications.

It would be a further advantage to provide a polyurethane that preventsoutgassing when applied onto a substrate. The ability to preventoutgassing would enable the use of the polyurethane on a variety ofsubstrates and decorative articles.

BRIEF DESCRIPTION OF THE DRAWINGS

The above, as well as other advantages of the present invention, willbecome readily apparent to those skilled in the art from the followingdetailed description when considered in the light of the accompanyingdrawings in which:

FIG. 1 is a cross-sectional view of an article formed utilizing thepolyurethane of the present invention;

FIG. 2 is a cross-sectional view of another article formed utilizing thepolyurethane of the present invention; and

FIG. 3 is a cross-sectional view of an article using a three-dimensionalsubstrate and the polyurethane of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The preferred polyurethane of the present invention has primaryaliphatic isocyanate crosslinking. The polyurethane is the reactionproduct of a two component system. The resulting reaction mass of thetwo components is generally solvent-free. In accordance with theinvention, solvent free means that the reaction mass contains an amountof water or organic solvents at levels that do not adversely affect theviscosity of the reaction mass and thereby prevent the formation of alens. Additionally, the amount of water or organic solvent mustsufficiently evaporate upon curing in order to prevent the formation ofstriations, parting lines, or bubbles in the cured polyurethane.Preferably, solvent-free means there is less than about five weightpercent water or organic solvents in the combined admixture of thereaction components. More preferably, the solvent content in thecombined reaction components is less than about one weight percent.

The first reaction component contains one or more polyols, optionally,one or more diols, and a catalyst. The polyols utilized in accordancewith the present invention are compounds having 3 or more hydroxylgroups. The polyols are generally selected from the group consisting ofpolyesters, polycarbonates, polyacrylates, polyalkylenes, andpolyethers, or combinations thereof. The polyol, or combined polyols,have an equivalent weight in the range of about 28 to about 3000. In thepresent invention, equivalent weight corresponds to the molecular weightof the material divided by the number of hydroxyl groups. Combinationsof polyols within the noted equivalent weight limitation may be suitablefor use with the invention. However, the amount of polyether in thefirst reaction component, whether provided as a polyol or diol,preferably should not exceed about 40 weight percent of the firstcomponent. Amounts of polyethers in excess of the noted limitation canadversely affect the clarity or the weathering properties of the presentinvention. Desirably, polyester based polyols and diols, forming greaterthan about 20 weight percent polyester in the first reaction component,are used in the present invention in order to improve outdoordurability. The polyol comprises in the range from greater than about 10weight percent of the first reaction component.

Optionally, one or more diols are included in the first reactioncomponent. The diols are compounds that have two hydroxyl groups. Inaddition to polyester diols, polycarbonate, polyacrylate, polyalkylene,and polyether diols, or combinations of the noted compounds, may beutilized in the present invention. The one or more diols have a combinedequivalent weight in the range of about 30 to about 4000. Additionally,the diols comprise in the range up to about 65 weight percent of thefirst reaction component. Desirably, the diols include the combinationof a short chain diol, having an equivalent weight in the range fromabout 30 to about 400, and a polymeric, or long chain diol having anequivalent weight in the range of from about 400 to about 4000.Additionally, it has been found that when a polyester and a polyetherare utilized in the first reaction component, the combined amount ofpolyether, whether provided as a polyol or diol, preferably should notexceed about 40 weight percent of the first reaction component.

The first reaction component of the present invention also requires acatalyst. The isocyanate groups of the second component react with thehydroxyl groups of the first component under the influence of thecatalyst to form urethane linkages. Conventional catalysts generallyrecognized for use in the polymerization of urethanes may be suitablefor use with the present invention. For example, aluminum, bismuth, tin,vanadium, zinc, or zirconium based catalysts may be used with thepresent invention. Though not desired because of the their potentialtoxicity, mercury based catalyst may also be used. The desired catalystsare tin based catalyst. Tin based catalyst have been found tosignificantly reduce the amount of outgassing present in thepolyurethane. Most desirable are dibutyl tin compounds. Even moredesirable are the catalyst selected from the group consisting ofdibutyltin diacetate, dibutyltin dilaurate, dibutyltindiacetylacetonate, dibutyltin dimercaptide, dibutyltin dioctoate,dibutyltin dimaleate, dibutyltin acetonylacetonate, and dibutyltinoxide. The catalyst is preferably included at levels of at least 200 ppmin the first component and more preferably at 300 ppm or greater.

Optionally, the first reaction component of the present invention caninclude various additives. For example, leveling agents may be utilizedin the first reaction component to ensure a smooth finish to the exposedsurface of the polyurethane. A polyethylene oxide modified polymethylsiloxane can be utilized in the present invention as a leveling agent.However, other leveling agents generally recognized by one of ordinaryskill in the art may also be suitable for use with the invention. Theleveling agents are desirably included in the range from about 0.01weight percent to about 1 weight percent.

Another additive to the first component can include UV absorbers whichimprove the weather resistance of the polyurethane top coal. The UVabsorbers generally recognized in the art may be suitable for use withthe invention. Alternatively, a hindered amine radical scavenger can beincluded in the first reaction component or combined with an UVabsorber. The hindered amine free radical scavengers generallyrecognized in the art contribute to photostabilization of thepolyurethane by trapping alkoxy and hydroxy radicals produced bylight-induced dissociation of hydroperoxides. The amount of UV absorberin the first component is desirably in the range from about 0.1 weightpercent to about 4 weight percent. The amount of hindered amine radicalscavenger in the first component in desirably in the range of about 0.1weight percent to about 2 weight percent.

Additionally, moisture scavengers, antioxidants, and antifoaming agentscan be included with the first reaction component. Conventionalcompounds of the noted categories generally recognized by those skilledin the art may be suitable for use in the present invention to improvethe finished properties of the polyurethane. Moisture scavengers aredesirably included at levels in the range of about 0.1 weight percent toabout 3 weight percent. The antioxidant is desirably included in a rangeof about 0.1 weight percent to about 2 weight percent. Antifoamingagents are desirably included in an amount from about 0.2 weight percentor less.

Other compounds, such as coloring agents and decorative solids, can beadded to the first component to enhance to the aesthetics of thefinished polyurethane. Coloring agents, such as pigments or dyes, areincluded at various levels to obtain a desired effect. Decorative solidscould include such items as metal flakes, polymeric flakes, glitter,beads, or other materials that provide a decorative feature to thefinished polyurethane. The decorative solids are also included invarious amounts to obtain a desired effect to the finished article.

In accordance with the present invention, a second component is providedwhich includes a primary aliphatic isocyanate crosslinker, andpreferably a primary aliphatic polyisocyanate crosslinker. A primaryisocyanate is defined as one having a carbon atom that has an —NCO groupand two hydrogen atoms attached to the carbon atom. The primaryisocyanate is an important factor in providing a flexible polyurethanethat does not exhibit a substantial amount of outgassing. Outgassing canoccur when the isocyanate component of the polyurethan undesirablyreacts with a source of water or carboxyl groups and not the hydroxylgroups present in the first component.

In the present invention, it is preferred that the second reactioncomponent include a primary polyisocyanate in an amount of about 50weight percent or greater. This generally corresponds to polyisocyanatecrosslinking of about 25 weight percent or greater in the curedpolyurethane. The primary aliphatic polyisocyanate may be the onlyisocyanate source in the component or it may be combined with otherprimary aliphatic isocyanates, such as monomeric isocyanates. Theutilization of secondary isocyanates can result in the rigidpolyurethanes or polyurethanes which exhibit outgassing. Conventionalprimary aliphatic polyisocyanate crosslinkers may be suitable for usewith the present invention. For example, Desmodur XP-7100 and DesmodurN-3300 from Bayer Chemical of Pittsburgh, Pa. are two polyisocyanatessuitable for use with the invention. Additionally, the polyisocyanatemay be a blocked polyisocyanate to further enhance the reduction ofoutgassing in the cured polyurethane. Blocked polyisocyanates will notreact until a desired curing temperature is achieved, thereby furtherpreventing the undesired reaction of the isocyanate with water orcarboxyl groups. Polyisocyanate levels of at least about 50 weightpercent of the total isocyanate present in the second component maysubstantially reduce outgassing in the cured polyurethane.

The crosslink density of a polyurethane is calculated by dividing theweight of the reaction components having a functionality of three orgreater by the total weight of the polyurethane and multiplying by 100.Generally, rigid polyurethanes have relatively high cross link densitiesof 30% or higher. In accordance with the present invention, the use of aprimary aliphatic polyisocyanate results in a flexible polyurethaneshaving a high crosslink density. When the polyisocyanate content of thesecond reaction component is about 50 weight percent or greater,crosslink densities are 30 percent or greater, and preferably 40 percentor greater. The flexibility of the resulting urethanes, according to theflexural modulus tests are generally 1.0×10⁸ or less.

The first and second reaction components are combined to form asolvent-free admixture having an NCO:OH ratio of about 0.75 to about1.25. The reaction components, prior to mixing, are desirably maintainedat specified viscosity ranges. The viscosity measurements for thepresent invention were measured on a Brookfield Viscometer model RV withspindle number 4 at about 20 rpm. The viscosity of the first componentis desirably maintained in the range from about 200 cps to about 5000cps at 25° C. The viscosity of the second reaction component isdesirably maintained in the range from about 100 cps to about 5000 cpsat 25 C. Upon mixing, the viscosity of the admixture is in the rangefrom about 400 cps to about 5000 cps at 25° C., and desirably in therange from about 600 cps to about 4000 cps.

The viscosity of the uncured polyurethane is important in achieving adesired thickness and continuity in the cured polyurethane lens whenapplied over a substrate. The viscosity limitation also provides apourable reaction mass that flows well onto a substrate. It is desiredthat the reaction mass flow to the edge of the substrate and form aradius of curvature, without actually overflowing the substrate. Theviscosity limitation also enhances the ability to achieve desired layerthicknesses. A higher viscosity than the noted limitation may result instriations or parting lines in the finished polyurethane. A lowerviscosity will not permit the polyurethane to form the desired meniscusor lens over the substrate. The polyurethane of the present invention iscapable of achieving thicknesses of greater than 0.13 mm, and preferablygreater than 0.25 mm.

In accordance with the present invention, the admixture is applied ontoa substrate and cured to form a polyurethane coating. The curing of thepolymer may be accomplished by heating the material, applying infraredradiation, or curing at ambient temperatures. Other conventional curingtechniques recognized by those skilled in the art may be suitable foruse with the present invention. Desirably, the polyurethane is cured ina convection oven at 52° C. for about 10 hours. One advantage of thepresent invention over conventional polyurethane s is that thepolyurethane is tack free after about one hour of curing at about 52° C.The tack free polyurethane can then be handled without being completelycured.

Upon curing, the polyurethane of the present invention exhibits desiredflexbility, durability, and weather resistant properties. Preferably,the polyether segments, resulting from the use of polyether basedpolyols and diols in the first component, represent no more than 20weight percent in the cured polyurethane. More preferably, the polyethersegments in the cured polyurethane is about 15 weight percent or less. Apolyether content in excess of the noted limitation may adversely impactthe clarity and weathering properties of the cured polyurethane.

The flexibility of the present invention enables use of the polyurethaneon various articles. For example, the present invention may be utilizeas a protective layer on an adhesive backed substrate. The flexibilityof the polyurethane of the present invention enables the application ofthe coated article on curved or non-planer surfaces. The flexibilitysignificantly reduces the tendency of the polyurethane to spring back toits originally cured form after being bonded to a surface.

The flexibility of the polyurethane is demonstrated by the Shore Ahardness properties, the storage modulus, and the flexural modulus. TheShore A hardness test of the present inventive polyurethane is generallyless than 94, and preferably less than 92. Shore A hardness levels inexcess of 94 are considered stiff or rigid. The storage modulusindicates the rigidity of the polyurethane under tension. Thepolyurethanes of the present invention have a storage modulus of 1.0×10⁸or less. The flexural modulus measures the flexibility of thepolyurethane under tortional strain. The polyurethanes of the presentinvention have a flexural modulus of 1.0×10⁸ or less. Additionally, theflexibility of the polyurethane is often indicated by its self-healingcharacteristics, or the ability to return to its original shape upondeformation.

The durability and weathering properties of the present invention areimportant features which enable the use of the polyurethane in variousenvironments. For applications of the polyurethane in exteriorenvironments, the polyurethane must not yellow or significantly changecolor when exposed to environmental conditions. The present invention,when subjected to a heat aging test in accordance with ASTM D2244-79,exhibits a color shift within 1 delta E. Other environmental testsutilized to indicate acceptable exterior performance are the salt spraytest, the humidity resistance test, and the thermal shock test. Apolyurethane should remain clear and not cloudy or opaque uponcompletion of the noted tests. The durability of the polyurethane topcoat is measured by the Hoffman scratch resistance test which indicatesthe abrasion resistance of the material. The present invention generallyhas a Hoffman scratch resistance of 2 or less.

The polyurethane of the present invention may be applied to varioussubstrates to form a layer on the substrate, or a portion of thesubstrate. The substrate may include wood, polymeric material, fiberreinforced polymers, metal, or combinations thereof. The choice ofsubstrate is dependent upon the desired end use. Some examples ofcombined substances would include metal coated polymer films and polymersealed wood or wood veneer. The polyurethane of the present invention isideally suited for applications with substrates containing moisture orapplications permitting the direct or indirect contact of the isocyanatewith carboxyl groups. For example, a porous substrate with an adhesivebacking permits the indirect contact of the isocyanate in thepolyurethane reaction mass with carboxyl groups in the adhesive.

The polyurethane of the present invention is ideally suited for use informing decorative articles requiring a transparent layer. Somedecorative articles utilize a substrate with indicia applied onto thesubstrate. Indicia includes any distinctive marks or representations. Inaccordance with the present invention, the polyurethane may be applieddirectly onto the substrate and the indicia.

In the present invention, indicia could include such items as printedgraphics or three-dimensional graphics. Printed indicia may be appliedonto the substrate, for example, with solvent based inks, water-basedinks, UV inks, or powder inks. The printed indicia may be appliedthrough various processes including screen printing, flexo-printing,gravure printing, digital printing, off-set printing, and pad printing.Three dimensional graphics may also be applied onto the substrate ormay, by themselves, serve as the substrate. Three dimensional graphicsmay include for example, a cured polyurethane body with a tie layerbonded to the polyurethane. An adhesive is then applied to the opposingsurface of the tie layer. An example of three-dimensional graphics wouldinclude those disclosed in EP 0392847, herein incorporated by reference.Other types and styles of indicia may also be utilized with the presentinvention.

Alternatively, the article may include several different types or stylesof indicia applied, or layered upon the substrate. The polyurethane ofthe present invention is well suited for this style of applicationbecause it does not permit a substantial amount of outgassing. Thislayered style of indicia can directly expose an adhesive to the urethanetop coat. This type of application with a conventional polyurethaneoften results in a significant amount of outgassing in the curedpolyurethane. The present invention does not experience a substantialamount of outgassing, thereby enabling the direct exposure of theadhesive to the polyurethane.

FIG. 1 illustrates an article made in accordance with the presentinvention. The article 10 includes a polymeric base substrate 12 uponwhich the polyurethane top coat 14 of the present invention is applied.The polymeric base substrate 12 could desirably include polyvinylchloride, polyester, acrylic polymers, polycarbonates, polyurethanes,polyethylene acrylic acid copolymer, polyvinylacetates, and reflectivesheeting. An adhesive 16 may be attached to a surface 18 of thesubstrate 12 opposite the surface 20 upon which the polyurethane 14 isapplied. The adhesive may include various adhesive attachment systems,for example, pressure sensitive adhesives, contact adhesives, hot meltadhesives, and structural adhesives. A release liner 22 is attached tothe adhesive 16 until removed upon final application of the article 10to a desired surface (not shown). The substrate 12 includes indicia 24applied onto surface 20 of the substrate 12. The indicia 24 is coveredby the polyurethane top coat 14.

Another embodiment of the present invention is depicted in FIG. 2. FIG.2 generally includes an article 30 having a base substrate 32 and apolyurethane top coat 34 applied over the substrate. Affixed to thesubstrate 32 is an adhesive 36. A removable release liner 38 is attachedto the adhesive. A first layer of indicia 40 is applied to a surface ofthe substrate 32. A second article containing indicia 42 is then appliedover the first layer of indicia 40. The second article 42 includes asubstrate 44, an adhesive 46, and indicia 48 applied to the substrate 44opposite the adhesive 46. The polyurethane top coat 34 of the presentinvention is applied over the base substrate 32 and the second article42.

FIG. 3 illustrates another embodiment of the present invention. Thearticle 50 includes a three dimensional substrate 52. A polyurethane topcoat 54 is applied over the three dimensional substrate 52. A releaseliner 56 is applied to a surface of the substrate opposite thepolyurethane top coat 54.

The following non-limiting examples further illustrate the presentinvention. Unless otherwise indicated, the following test procedureswere used in the examples. The particular materials and amounts recitedin these examples, as well as other conditions and details, are to beinterpreted broadly in the art and should not be construed to undulyrestrict or limit the invention in any way.

Test Methods

Hoffmnan Scratch and Mar Resistance Test:

The scratch and mar of the polyurethanes were measured by aBalanced-Beam Scrape tester described in ASTM-2197-86. The Hoffmanstylus was held at 45 degrees from vertical with the top sloping in thedirection of test sample travel. The stylus was held in place by afulcrum elevated at 22 degrees. A 1000-Gram-weight was placed on theweight support. The beam was lowered until the loop rested on top of thetest specimen, following which the sliding platform was slowly pushedacross the specimen. The scratch test was performed at 25° C. Asuccessful test will result in the polyurethane coat showing nopermanent injury, scratch, or defect after 1 hour.

Humidity Resistance:

The polyurethanes were applied over a tin vapor coated polyester filmand cured. Each sample was placed in a humidity condensing chamber with100% relative humidity at 38° C. for 7 days. The samples were observedfor cloudiness and corrosion upon removal from the chamber.

Heat Aging:

The polyurethanes were applied onto a white ink printed standard tincoated polyester substrate and cured. The samples were put in an 80° C.oven for 7 days. Upon removal, the polyurethane coat was observed todetermine any significant yellowing in color. The color difference orchange was measured by standard test ASTM D2244-79. The color difference(Delta E) was calculated by the CIE 1976 L* a* b* Uniform Color Spaceand Color-Difference Equation For successful results, the value of DeltaE shall not exceed 1.

Salt Spray:

The polyurethanes were applied onto a tin coated polyester substrate andcured. The samples were put into a salt spray chamber, which had 5% NaClsolution atomized at 35° C. Upon removal after 10 days, the samples wereobserved for cloudiness and corrosion.

Shore A Hardness:

Shore A Hardness was measured by Shore A Durometer according to ASTMD-2240.

Thermal Shock:

The polyurethanes were applied onto tin coated polyester and cured. Eachsample was tested at 10 cycles of the following tests:

4 Hours at −30° C.

5 minutes immersion at 85° C. water.

The samples were observed for cloudiness and corrosion.

Storage Modulus Test:

The E′ (storage modulus) is a measure of flexibility of a material. Thestorage modulus was measured at 25° C. in tension using RheometricSolids Analyzer (RSA II) at a frequency of 6.28 rad/second. The tensionwas kept at 0.03% strain. The test sample, at a thickness of 1.8 mm andranging in size from 3.5 mm to 6.5 mm, was mounted with clamps andtightened. In oscillatory flow, a periodic strain of predeterminedamplitude and frequency is applied to the sample, and the stressresponse of the material is measured. The real part of the Fouriertransform of the response gives the elastic modulus, E′ (storagemodulus).

Flexural Modulus Test:

The flexural modulus was measured at 25° C. using Seiko DMS 110 at afrequency of 6.28 rad/second. A strip of sample, having a thickness of1.8 mm and ranging from 10 mm to 13 mm in width and 20 mm in length, wasmounted in the dual cantilever fixture. A strain amplitude of 30 micronswas used to determine the flexural modulus of the sample.

Substrates utilized in the Examples:

Substrate (1) was prepared by screen printing a Scotchcal™ 7900 Seriessolvent-based phosphorescent ink using a 110 mesh screen on Scotchlite™Reflective Engineering Sheeting both supplied from the Minnesota Miningand Manufacturing Company of St. Paul Minn. The ink was dried for 30minutes at 80° C. Substrates (2)-(4) were standard Scotchcal™ p-seriesfilms from the Minnesota Mining and Manufacturing Company. Substrate (5)was prepared by digitally printing a standard powder toner onto a whitePVC film. Substrate (6) was made by rotary printing Scotchcal™ 7900Series solvent-based black metallic ink with carbon fiber pattern onsilver PVC film. Substrate (7) was made by applying die-cut PVC graphicsonto a hologram polyester film substrate. Substrate (8) was an unclearedand uncut standard 3-Dimensional Graphics from the Minnesota Mining andManufacturing Co. Substrate (9) was made by applying uncleared/laser cut3-Dimensional Graphics on PVC woodgrain film. Substrate (10) wasprepared by screening Scotchcal™ 7900 Series solvent-based white inkwith 230 mesh screen on tin metallized film Substrate (11) was tinmetallize film.

EXAMPLE 1

The first component, which was polyester polyols/diols based, wasprepared by mixing 31.9 grams of Formrez-55-225, 30 grams ofFormrez-55-112, and 30 grams of Tone-301 in a round bottom flask andheated to 70° C. The admixture was agitated and de-gassed for 4 hours byvacuum (below about 30 inch Hg) until all the bubbles were stripped off.The temperature of the admixture was cooled down to about 50° C. and0.06 grams of T-12, 0.2 grams Silwet L-7607, 1.5 grams of Uvinul N-539and 1 gram of Tinuvin-292 were then added into the admixture. Theadmixture was agitated for 15 minutes. The formulation of the firstreaction component, by weight percent, is listed in Table 2.

The second reaction component included 100 grams of polyisocyanate(Desmodur XP-7100). The first and second reaction components were mixedin a one to one volume ratio and poured on the above noted elevensubstrates. The polyurethanes were cured 10 hours at 52° C. in aconvection oven. The cured polyurethane did not outgas on any of thesubstrates and had excellent optical clarity and flexibility.

Comparative Examples 1-4

The first component in comparative Examples 1 through 4 includesdifferent polyether based polyols and diols. The Examples were preparedaccording to the same procedure described in Example 1. The polyols anddiols utilized for each Example are noted in Table 1.

The second component for Comparative Example 1 was prepared by reacting30 grams of Pluracol TP-4040 and 70 grams of Desmodur W for 4 hours at80° C. The resulting second component was a mixture of a secondarypolyisocyanate and monomeric isocyanate (Desmodur W). The secondcomponent used in Comparative Example 2 was prepared by reacting 73.5grams of Desmodur I, with 23.5 grams of Desmophen L951, and 3 grams ofMultranol-4011 for 4 hours at 80° C. The resulting Part B comprises amixture of polyisocyanate with primary and secondary isocyanatefunctional groups and monomeric Desmodur I.

The polyurethanes were prepared by mixing the first and second reactioncomponents in a one to one volume ratio and then poured onto the notedsubstrates (1) to (11). The polyurethanes were cured 10 hours at 52° C.The polyurethanes in Comparative Examples 1, 2 and 4 were still tackywhen cured one hour at 52° C. convection oven or 10 minutes in IR ovenand they had severe outgas on substrates (1) to (9). The polyurethaneswere very rigid. The polyurethane in Comparative Example 3 was cloudy.

Examples 2-6

The first components used in Examples 2-6 were prepared according to thesame procedure described in Example 1. The composition of the firstcomponent for each Example is listed in Table 1.

The second component used in Example 2 was prepared by reacting 30 gramsof Pluracol-538, and 70 grams of Vestanat IPDI for 4 hours at 80° C. Theresulting second component included a mixture of polyisocyanate withprimary and secondary isocyanate groups and monomeric Vestanat IPDI. Thesecond component used in Example 3 was the same as the one utilized inComparative Example 1. The second component in Example 3 comprises amixture of second polyisocyanate and monomeric Desmodur W. The secondcomponent used in Example 4 was prepared by mixing 70 grams ofpolyisocyanate and 30 of Desmodur H. The second component used inExample 5 was prepared by mixing 50 grams of polyisocyanate and 50 gDesmodur H.

The polyurethanes were prepared by mixing the first component and thesecond component in a one to one volume ratio and then applied tosubstrates (1) through (11). The polyurethanes were cured for 10 hoursat 52° C. The polyurethanes in Examples 2 and 3 showed severe outgas onsubstrates (1) through (9). Although not indicated in the Table, theweathering properties of the Examples 2 and 3 are improved overconventional polyurethanes. Additionally, Examples 2 and 3 were rigid.The flexible polyurethane in Examples 4 and 6 were clear and did notexhibit any outgassing on any of the substrates. The polyurethane inExample 5 exhibited outgassing on substrates (1), (5) and (9).

Comparative Examples 5-8 and Examples 7-12

The polyester polyol/diol based first components in Examples 5 through12 were prepared according to the same procedure described inExamples 1. The ingredients and amounts used for each Example aresummarized in Table 4. The type of catalyst was varied for each Example.The various catalysts indicated in the Table.

The polyurethanes were prepared by mixing the first and second reactioncomponents in a one to one volume ratio and then poured onto substrates(1) through (9). The polyurethanes were cured for 10 hours at 52° C. Thepolyurethane in Examples 7, 9, 10 and 12 didn't outgas and were flexibleand optically clear. Comparative Examples 7 and 8 showed severeoutgassing on all the substrates tested.

Examples 13-18

The first components utilized in Examples 13-17 were prepared accordingto the same procedure described in Example 1. The ingredients werevaried in order to demonstrate the effect of varying polyether contentson the cured polyurethane. The ingredients and amounts utilized aresummarized in Table 5. Additionally, Example 18 included a black pigmentadded to the first reaction component.

The second component in Example 16 was the same as the one used inComparative Example 2. The second component in Example 17 was the sameone utilized in Comparative Example 1. Examples 13 through 15 and 18utilized a polyisocyanate. The amount of the second component used ineach Example is listed in Table 5.

The polyurethanes for Examples 13-17 were prepared by mixing the firstand second components in a one to one volume ratio and then poured ontosubstrates (1) through (11). The polyurethanes were cured for 10 hoursat 52° C. The black pigmented polyurethane in Example 18 was only castonto substrate (4), a black PVC film. The polyurethane in Example 18 wascured the same way as described in Examples 13-17. The polyurethane inExample 13 was cloudy and therefore unacceptable. The polyurethane inExamples 14 and 15 did not outgas and were clear and flexible. Thepolyurethanes in Examples 15 and 16 exhibited outgassing on all thesubstrates tested. Both the Examples were rigid. The pigmentedpolyurethane in Example 18 was flexible and did not exhibit anyoutgassing.

TABLE 1 Materials Used in The Invention. Designation DescriptionSupplier Formrez ™-55-225 Polyester diol (—OH, Eq Wt = 245) WitcoChemical, Tarrytown, N.Y. Formrez ™-55-112 Polyester diol (—OH, Eq Wt =500) Witco Chemical, Tarrytown, N.Y. Tone ™-301 Caprolactone-basedpolyester Union Carbide, Danbury, CT triol (—OH, Eq Wt = 100) Tone ™-305Caprolactone-based polyester Union Carbide, Danbury, CT triol (—OH, EqWt = 180) Pluracol ™ 538 Poly(propylene oxide) based BASF, Mount Oliver,N.J. triol (—OH, Eq Wt = 1603) Pluracol ™ TP-4040 Poly(propylene oxide)based BASF, Mount Oliver, N.J. triol (—OH, Eq Wt = 1368) Pluracol ™-220Poly(propylene oxide) based BASF, Mount Oliver, N.J. triol (—OH, Eq Wt =2078) Multranol-4011 Poly(oxyalkylene) ether Bayer Corp, Pittsburgh, PA(Eq Wt = 100) Desmophen L951 Poly(oxyalkylene) ether Bayer Corp,Pittsburgh, PA (Eq Wt = 213) Vestanat ™ IPDI Isophorone diisocyanateHULS America Inc., Piscataway, N.J. Desmodur ™ I Isophorone diisocyanateBayer Corp, Pittsburgh, PA Desmodur ™ W Bis(4-isocyanatocyclohexyl)Bayer Corp, Pittsburgh, PA methane (Eq Wt = 132) Tolanate ™ HDT-LVPolyisocycanate (Eq Wt = 183) Rhodia, Inc., Teaneck, N.J. Desmodur ™ H1,6-hexamethylene diisocyanate Bayer Corp, Pittsburgh, PA (—NCO, Eq Wt =84) Desmodur ™ XP-7100 Polyisocyanate (Eq Wt = 205) Bayer Corp,Pittsburgh, PA Metacure ™T-12 Dibutyl tin dilaurate Air Products andChemicals, Allentown, PA Metacure ™T-9 Stannous octoate Air Products andChemicals, Allentown, PA Cotin ™-222 Tin carboxylate Caschem, Carlstadt,N.J. Cotin ™-430 Diocyltin dicarboxylate Caschem, Carlstadt, N.J.Formrez ™ SUL-3 Dibutyl tin diacetate Witco Chemical, Tarrytown, N.Y.Formrez ™ UL-22 Dibutyl tin dimercaptide Witco Chemical, Tarrytown, N.Y.Formrez ™ UL-29 Dimethyl tin dimercaptide Witco Chemical, Tarrytown,N.Y. Octoate Z Zinc ethyloctoate Vanderbilt, Norwalk, CT K-Kat ®-8201Dibutyl tin bis(acetylacetonate) King Industries, Norwalk, CT Uvinul ™N-539 UV-Light Absorber BASF, Parsippany, N.J. Tinuvin ™-292 HinderedAmine Ciba-Geigy, Hawthorne, N.Y. Irgarol ™-1051 Fungicide Ciba-Geigy,Hawthorne, N.Y. Skane M-8 Fungicide Rhom and Haas, edison, N.J. Silwet ™L-7607 Polyethylene Oxide Modified Witco Chemical, Tarrytown, N.Y.Polymethyl siloxane Silwet ™ L-77 Polyethylene Oxide Modified WitcoChemical, Tarrytown, N.Y. Polymethyl siloxane Zapon ™ Black R LiquidWater-Based Jet Black Dye BASF, Rensselaer, N.Y. Scotchlite ™Engineering Reflective Substrate with 3M, St. Paul, MN Grade ReflectiveSheeting Pressure Sensitive Adhesive 3-Dimensional Graphics 3Dimensional Graphics with 3M, St. Paul, MN Pressure Sensitive Adhesive

TABLE 2 Polyether based Polyurethanes Cured on Various Substrates. Comp.Comp. Comp. Comp. 1^(st) component (grams) Exp. 1 Exp. 2 Exp. 3 Exp. 4Pluracol-200 — 40.0 — — Multranol-4011 35.0 38.8 35.0 35.0 Pluracol 53836.8 — 36.8 36.8 Desmophen L951 27.7 21.3 27.7 27.7 T-12 0.06 0.06 0.060.06 Uvinul N-539 1.0 1.0 1.0 1.0 Tinuvin-292 1.0 1.0 1.0 1.0 SilwetL-7607 0.3 0.3 0.3 0.3 Silwet L-77 — — — — 2^(nd) component: 100.0 — — —30 grams Pluracol TP-4040 + 70 grams Desmodur W 2^(nd) component: —100.0 — 100.0 73.5 grams Desmodur I + 23.5 grams of Desmophen L951 + 3grams Multranol-4011 2^(nd) component: — — 100.0 — Desmodur XP-7100X-link density (%) 50.9% 52.6% 85.9% 49.1% (wt %) Polyetherpolyols/diols in 65% 63.3% 50% 63.3% urethane top coat Isocyanate used2° 1° & 2° 1° 1° & 2° Clarity of urethane top coat Clear Clear MilkyClear White Flexibility of urethane top coat Rigid Rigid — Rigid (1)Cured on phosphorescent ink Outgas Outgas — Outgas (2) Cured on bluepearl PVC film Outgas Outgas — Outgas (P-5338) (3) Cured on woodgrainPVC. Outgas Outgas — Outgas (4) Cured on black PVC film Outgas Outgas —Outgas (P-3098) (5) Cured on 3M digital printed Outgas Outgas — Outgasgraphics on white PVC film (6) Cured on 3M inks printed Outgas Outgas —Outgas graphics on silver PVC film (P-3450) (7) Cured on PVC graphics onOutgas Outgas — Outgas hologram polyester (8) Cured on uncleared/uncutOutgas Outgas — Outgas 3-dimensional graphics. (9) Cured on3-dimensional Outgas Outgas — Outgas graphics on woodgrain PVC (10)White ink printed standard tin OK OK — OK coated polyester substrate.(11) Tin coated polyester substrate OK OK — OK

TABLE 3 Polyether-Based Polyurethanes Cured on Various Substrates.1^(st) component (grams) Exp. 1 Exp. 2 Exp. 3 Exp. 4 Exp. 5 Exp. 6Formrez-55-225 31.9 30.6 30.6 31.9 31.9 36.8 Formrez-55-112 30.0 30.530.5 30.0 30.0 — Tone-305 — 26.1 26.1 — — 59.8 Tone-301 30.0 — — 30.030.0 — T-12 0.06 0.06 0.06 0.06 0.06 0.045 Uvinul N-539 1.5 1.4 1.4 1.51.5 1.5 Tinuvin-292 1.0 1.4 1.4 1.0 1.0 1.0 Irgarol-1051 — — — — — 0.8Skane M-8 — — — — — 0.5 Silwet L-7607 0.2 — — 0.5 0.5 0.3 Silwet L-77 —0.15 0.15 — — — 2^(nd) component: — — 100 — — — 30 grams PluracolTP-4040 + 70 grams Desmodur W 2^(nd) component: — 100.0 — — — — 70 gramsVestanat IPDI + 30 grams Pluracol-538 2^(nd) component: 100.0 — — — — —Desmodur XP-7100 2^(nd) component: — — — — — 100.0 Tolanate HDT-LV2^(nd) component: — — — 75.0 — — Desmodur XP-7100/Desmodur H = 70/30 byweight 2^(nd) component: — — — — 62.0 — Desmodur XP-7100/Desmodur H =50/50 by weight X-link density (%) 65% 26.3% 28.0% 41.2% 30% 79.9%Isocyanate used 1° 1° & 2° 2° 1° 1° 1° Clarity of urethane top coatClear Clear Clear Clear Clear Clear Flexibility of urethane top coatFlexible Rigid Rigid Flexible Flexible Flexible (1) Cured onphosphorescent ink OK Outgas Outgas OK Outgas OK (2) Cured on blue pearlPVC OK Outgas Outgas OK OK OK (P-5338) (3) Cured on woodgrain PVC filmOK Outgas Outgas OK OK OK (4) Cured on black PVC film OK Outgas OutgasOK OK OK (P-3098) (5) Cured on 3M digital printed OK Outgas Outgas OKOutgas OK graphics on white PVC film (6) Cured on 3M inks printed OKOutgas Outgas OK OK OK graphics on silver PVC film (P-3450) (7) Cured onPVC graphics on OK Outgas Outgas OK OK OK hologram polyester substrate(8) Cured on uncleared/uncut OK Outgas Outgas OK OK OK 3-dimensionalgraphics. (9) Cured on 3-dimensional OK Outgas Outgas OK Outgas OKgraphics on woodgrain PVC film (10) White ink printed standard tin OK OKOK — — OK coated polyester substrate. (11) Tin coated polyestersubstrate OK OK OK — — OK

TABLE 4 Polyurethanes Made from Polyester Polyols/Diols ComprisingDifferent Catalysts in the First Component and Cured on VariousSubstrates. Comp. Comp. Comp. Comp. 1^(st) component (grams) Exp. 5 Exp.7 Exp. 8 Exp. 9 Exp. 10 Exp. 11 Exp. 6 Exp. 7 Exp. 8 Exp. 12Formrez-55-225 31.9 31.9 31.9 31.9 31.9 31.9 31.9 31.9 31.9 31.9Formrez-55-112 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0Tone-301 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 1. MetacureT-9 0.06 — — — — — — — — — 2. Cotin-222 — 0.06 — — — — — — — — 3. Cotin430 — — 0.06 — — — — — — — 4. Formrez SUL-3 — — 0.06 — — — — — — 5.Formrez UL-22 — — — — 0.06 — — — — — 6. Formrez UL-29 — — — — — 0.06 — —— — 7. Bismuth Neodecanoate, 20% — — — — — — 0.35 — — — 8. ZincNeodecanoate, 16% — — — — — — — 0.44 — — 9. Octoate Z — — — — — — — —0.5 — 10. K-Kat-8201 — — — — — — — — — 0.06 Uvinul N-539 1.5 1.5 1.5 1.51.5 1.5 1.5 1.5 1.5 1.5 Tinuvin-292 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.01.0 Silwet L-7607 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 2^(nd)component: 100 100 100 100 100 100 100 100 100 100 Desmodur XP-7100 (1)Cured on phosphorescent ink Severe OK OK OK OK Outgas Outgas SevereSevere OK Outgas Outgas Outgas (2) Cured on blue pearl PVC film OK OK OKOK OK OK OK Severe Severe OK (P-5338) Outgas Outgas (3) Cured onwoodgrain PVC film OK OK OK OK OK OK OK Severe Severe OK Outgas Outgas(4) Cured on black PVC film OK OK OK OK OK OK Outgas Severe Severe OK(P-3098) Outgas Outgas (5) Cured on 3M digital printed Outgas OK OutgasOK OK Outgas OK Severe Severe OK graphics on white PVC film OutgasOutgas (6) Cured on 3M inks printed OK OK OK OK OK OK OK Severe SevereOK graphics on silver PVC film Outgas Outgas (P-3450) (7) Cured on PVCgraphics on Outgas OK OK OK OK OK OK Severe Severe OK hologram polyesterOutgas Outgas (8) Cured on uncleared/uncut OK OK OK OK OK OK OK SevereSevere OK 3-dimensional graphic Outgas Outgas (9) Cured on 3-dimensionalOK OK OK OK OK OK OK Severe Severe OK graphics on woodgrain PVC filmOutgas Outgas

TABLE 5 Clarity of Polyurethanes Made from a Mixture ofPolyester/Polyether Polyols/Diols in the First Component and Cured byPrimary and Secondary Polyisocyanates. 1^(st) component (grams) Exp. 13Exp. 14 Exp. 15 Exp. 16 Exp. 17 Exp. 18 Tone-301 20.3 25.0 25.0 20.320.3 30.0 Pluracol-538 — — — — — — Formrez-55-225 — — — — — 31.9 Voranol230-660 — — — — — — Formrez-55-112 — — — — — 30.0 Desmophen L-951 49.430.0 33.0 49.4 49.4 — Formrez-33-112 29.5 43.0 — 29.5 29.5 — Zapon blackR liquid — — — — — 1.5 Formrez-8056-143 — — 41.2 — — — Multranol-4011 —— — — — 35.0 T-12 0.06 0.06 0.06 0.06 0.06 0.07 Silwet L-7607 0.3 0.40.4 0.3 0.3 0.30 Uvinul N-539 0.4 0.3 0.2 0.4 0.4 1.5 Tinuvin-292 — 0.20.2 — — 1.5 2^(nd) component: — — — 100 — — 73.5 grams Desmodur I +Grams Desmophen L951 + 3 grams Multranol-4011 2^(nd) component: — — — —100 — 30 grams Pluracol TP-4040 + 70 grams Desmodur W 2^(nd) component:100 100 100 — — 100 Desmodur XP-7100 Isocyanate used 1° 1° 1° 1° & 2° 2°1° X-lik density (%) 60.1% 62.5% 62.5% 23.4% 25.1% 62.5% (wt %) ofPolyether polyols/diols 24.9% 15.0% 16.5% 52.7% 54.4% 64.2% in urethanetop coat Clarity of urethane top coat Milky Clear Clear Clear ClearClear White Flexibility of urethane top coat — Flexible Flexible RigidRigid Flexible (1) Cured on phosphorescent ink. — OK OK Outgas Outgas —(2) Cured on blue pearl PVC — OK OK Outgas Outgas — (P-5338). (3) Curedon woodgrain PVC film. — OK OK Outgas Outgas — (4) Cured on black PVC —OK OK Outgas Outgas OK (P-3098). (5) Cured on 3M digital printed — OK OKOutgas Outgas — graphics on white PVC film. (6) Cured on 3M inks printed— OK OK Outgas Outgas — graphics on silver PVC (P-3450). (7) Cured onPVC graphics applied — OK OK Outgas Outgas — on hologram polyester film.(8) Cured on uncleared/uncut — OK OK Outgas Outgas — 3-dimensionalgraphics. (9) Cured on 3-dimensional — OK OK Outgas Outgas — graphics onwoodgrain PVC film. (10) White ink printed standard tin — OK OK OK OK —coated polyester substrate. (11) Standard tin coated polyester. — OK OKOK OK —

TABLE 6 Specification Test Results Comp. Comp. Comp. Examples Exp. 1Exp. 2 Exp. 13 Exp. 14 Exp. 4 Exp. 1 Exp. 6 Type of Polyols/ PolyetherPolyether Polyester/ Polyester/ polyether polyester polyester Diols inPart A polyether polyether Flexibility 94 98 81 81 97 84 89 (Shore AHardness) Storage Modulus — 6.1 × 10⁸ 1.3 × 10⁷ 1.4 × 10⁷ 4.5 × 10⁸ 1.5× 10⁷ — (Pascal) Flexural Modulus — 9.5 × 10⁸ 2.8 × 10⁷ 2.2 × 10⁷ 7.2 ×10⁸ 2.7 × 10⁷ — (Pascal) Hoffman scratch test: Scratched Scratched OK OKScratched OK OK (1 kg. Weight load). (4) (5) (1) (2) (4) (1) (1) (from ascale 1 to 5) Color shift (DE*): 2.23 1.13 1.06 1.17 2.04 0.72 0.77 Heatage 7 days @ 80° C. Salt spray: 10 days, Clear Slightly Clear ClearClear Clear Clear 5% NaCl (DIN50021) Cloudy Humidity resistance: ClearClear Cloudy Cloudy Clear Clear Clear 7 days @ 38° C., 100% R.H. ThermalShock: Clear Slightly Slightly Slightly Clear Clear Clear Cloudy CloudyCloudy

Discussion of Examples and Tables 2-6

Tables 2 and 3 illustrate the impact of primary and secondaryisocyanates on the flexibility of the resulting polyurethanes. TheExamples utilizing a primary isocyanate resulted in flexiblepolyurethanes. The Examples utilizing secondary isocyanates, or acombination of primary and secondary isocyanates, result in a rigidpolyurethane. Additionally, the Examples indicate that the use ofsecondary isocyanates results in outgassing in the cured polyurethane.Comparative Example 3 in Table 2 indicates that the use of polyethercompounds in an amount of about 50 weight percent resulted in an unclearpolyurethane. Additionally, the Tables indicate that the Examplesutilizing a primary aliphatic polyisocyanate resulted in flexiblepolyurethanes with crosslink densities at the same level or higher thanthe rigid polyurethanes.

Table 4 represents the results of bismuth, tin, and zinc based catalystson the polyurethane of the present invention. The bismuth and zinc basedcatalysts resulted in outgassing in the cured polyurethane. The tinbased performed much better and only exhibited outgassing on a few typesof substrates. The dibutyl tin compounds did not exhibit any outgassing.

The results of the mixed polyether/polyester polyurethanes are listed inTable 5. The results indicate that secondary isocyanates produced rigidpolyurethanes. Additionally, the use of secondary isocyanates results inoutgassing. Example 13, with a polyether content in excess of 20 weightpercent, was milky white. The Examples utilizing a primarypolyisocyanate were flexible and did not outgas. Example 18 demonstratedthe use of a black pigment in the first reaction component.

Table 6 illustrates flexibility, durability and weather resistantproperties of the polyurethanes, The Examples 1,6, 13, and 14 indicatethat the polyurethanes produced in accordance with the present inventionexhibit improved flexibility and durability properties over theComparative Examples. The flexibility and durability of thepolyurethanes are demonstrated through the Shore A hardness, storagemodulus, flexural modulus, and Hoffman scratch tests. Additionally, thepolyester based polyurethanes exhibited improved weathering propertiesas represented through the salt spray, humidity resistance, and thermalshock tests.

In accordance with the provisions of the patent statutes, the presentinvention has been described in what is considered to represent itspreferred embodiment. However, it should be noted that the invention canbe practiced otherwise than as specifically illustrated and describedwithout departing from its spirit and scope.

What is claimed is:
 1. An article comprising: a) a substrate selectedfrom polymeric material, wood, fabric, reinforced polymers, metal,reflective sheeting, and a combination thereof, wherein the polymericmaterial or the polymer of the reinforced polymer comprises a polyvinylchloride, polyester, acrylic polymer, polycarbonate, polyurethane,polyethylene acrylic acid copolymer, or polyvinyl acetate; and b) aclear polyurethane applied as a protective layer on a first surface ofsaid substrate, said polyurethane is a reaction product of, i) a firstcomponent comprising one or more polyols having an equivalent weight inthe range from about 28 to about 3000, optionally one or more diolshaving an equivalent weight in the range from about 30 to about 4000,and a catalyst; and ii) a second component comprising at least 50 weightpercent of a primary polyisocyanate having a functionality of at leastthree, and wherein the first and second components together are solventfree.
 2. An article as recited in claim 1, wherein an adhesive isapplied onto a second surface of said substrate opposite to the firstsurface of said substrate.
 3. An article as recited in claim 1, furthercomprising indicia applied onto the first surface of said substrate andcovered by said polyurethane.
 4. An article as recited in claim 3,wherein said indicia is three dimensional.
 5. An article as recited inclaim 3, wherein said polyurethane layer covers all exposed surfaces ofthe indicia and the first surface of said substrate.
 6. An article asrecited in claim 4, wherein said three dimensional indicia comprises acured polyurethane body having a mounting surface, a tie layer bonded tothe mounting surface, and an adhesive body adhered to the tie layer. 7.An article as recited in claim 1, wherein said substrate is a basesubstrate and one or more secondary articles are applied over said basesubstrate, each of said secondary articles comprising an adhesiveattachment system, a substrate, and indicia.
 8. An article as recited inclaim 7, wherein said base substrate includes indicia and said secondaryarticles are applied over the indicia of said base substrate.
 9. Anarticle as recited in claim 7, wherein said one or more secondaryarticles include three dimensional articles.
 10. An article as recitedin claim 1, wherein said catalyst is a tin-based catalyst and saidpolyurethane, upon exposure to moisture or carboxyl groups, does notexhibit a substantial amount of outgassing.
 11. An article as recited inclaim 1, wherein the second component further comprises one or moremonomeric isocyanates.
 12. An article as recited in claim 1, wherein thefirst and second components form a solvent-free admixture having anNCO:OH ratio of about 0.75 to about 1.25.
 13. An article as recited inclaim 1, wherein the polyurethane contains up to about 20 weight percentof polyether segments.
 14. An article comprising: a) a substrateselected from polymeric material, wood, fabric, reinforced polymers,metal, reflective sheeting, and a combination thereof, wherein thepolymeric material or the polymer of the reinforced polymer comprises apolyvinyl chloride, polyester, acrylic polymer, polycarbonate,polyurethane, polyethylene acrylic acid copolymer, or polyvinyl acetate;and b) a clear protective polyurethane layer on a first surface of thesubstrate, wherein the polyurethane contains primary aliphaticisocyanate crosslinking, and wherein about 25% or more of the totalcrosslink density is contributed by a polyisocyanate components, saidpolyurethane exhibiting at least one property selected from the groupconsisting of a flexural modulus of 1.0×108 pascals or less, a storagemodulus of 1.0×108 pascals or less, a Shore A hardness of less than 94,a Hoffman scratch-hardness test result of 2 or less, and a color shift,in accordance with heat aging test ASTM D2244-79, within 1 delta E. 15.An article as recited in claim 14, wherein the polyurethane is areaction product of: (i) a first component comprising one or morepolyols having an equivalent weight in the range from about 28 to about3000, optionally one or more diols having an equivalent weight in therange from about 30 to about 4000, and a catalyst; and (ii) a secondcomponent comprising at least 50 weight percent of a primarypolyisocyanate having a functionality of at least three, and wherein thefirst and second components together are solvent free.
 16. An article asrecited in claim 14, further comprising indicia on a portion of thefirst surface of the substrate, wherein the polyurethane covers allexposed surfaces of the indicia and the first surface of said substrate.17. An article as recited in claim 14, further comprising an adhesivelayer on a second surface of the substrate, wherein the second surfaceis opposite the first surface of said substrate.
 18. An articlecomprising: a) a substrate having a first surface, said substrateselected from polymeric material, wood, fabric, reinforced polymers,metal, reflective sheeting, and a combination thereof, wherein thepolymeric material or the polymer of the reinforced polymer comprises apolyvinyl chloride, polyester, acrylic polymer, polycarbonate,polyurethane, polyethylene acrylic acid copolymer, or polyvinyl acetate;b) indicia on at least a portion of the first surface of the substrate;and c) a clear polyurethane applied as a protective layer over theindicia and any exposed portions of the first surface of said substrate,wherein the polyurethane is a reaction product of: i) a first componentcomprising one or more polyols having an equivalent weight in the rangefrom about 28 to about 3000, optionally one or more diols having anequivalent weight in the range from about 30 to about 4000, and acatalyst; and ii) a second component comprising at least 50 weightpercent of a primary polyisocyanate having a functionality of at leastthree, and wherein the first and second components together are solventfree; wherein the first and second components form a solvent-freeadmixture having an NCO:OH ratio of about 0.75 to about 1.25.
 19. Anarticle as recited in claim 18, further comprising an adhesive layer ona second surface of the substrate, wherein the second surface isopposite the first surface of said substrate.
 20. An article comprising:a) a substrate selected from polymeric material, wood, fabric,reinforced polymers, metal, reflective sheeting, and a combinationthereof, wherein the polymeric material or the polymer of the reinforcedpolymer comprises a polyvinyl chloride, polyester, acrylic polymer,polycarbonate, polyurethane, polyethylene acrylic acid copolymer, orpolyvinyl acetate; and b) a flexible clear polyurethane applied as alayer on a surface of said substrate, said flexible polyurethanecomprising a reaction product of, i) a first component included one ormore polyols having an equivalent weight in the range from about 28 toabout 3000, optionally one or more diols having an equivalent weight inthe range from about 30 to bout 4000, and a catalyst; and ii) a secondcomponent comprising a primary aliphatic isocyanate crosslinker havingat least 50 weight percent polyisocyanate, wherein the first and secondcomponents together are solvent free.
 21. An article as recited in claim1, wherein the first component comprises greater than about 20 weightpercent polyester.
 22. An article as recited in claim 1, wherein theprimary polyisocyanate comprises a primary aliphatic polyisocyanate. 23.An article as recited in claim 18, wherein the first component comprisesgreater than about 20 weight percent polyester.
 24. An article asrecited in claim 18, wherein the primary polyisocyanate comprises aprimary aliphatic polyisocyanate.
 25. An article as recited in claim 20,wherein the first component comprises greater than about 20 weightpercent polyester.
 26. An article as recited in claim 14, wherein thefirst component comprises greater than about 20 weight percentpolyester.
 27. An article as recited in claim 1, wherein said clearpolyurethane protective layer has a curved outer surface.
 28. An articleas recited in claim 14, wherein said clear protective polyurethane layerhas a curved outer surface.
 29. An article as recited in claim 18,wherein said clear polyurethane protective layer has a curved outersurface.
 30. An article as recited in claim 20, wherein said clearpolyurethane layer has a curved outer surface.
 31. The article of claim1, wherein at least a portion of the substrate is visible through thepolyurethane protective layer.
 32. The article of claim 14, wherein atleast a portion of the substrate is visible through the polyurethaneprotective layer.
 33. The article of claim 18, wherein at least aportion of the substrate is visible through the polyurethane protectivelayer.
 34. The article of claim 20, wherein at least a portion of thesubstrate is visible through the polyurethane protective layer.